Disclosed in U.S. Patent Application Publication No. 2009/0145504 is a high pressure fuel delivery pipe assembly for direct injection of fuel of this kind. The high pressure fuel delivery pipe assembly includes a fuel distribution tube in the form of an elongate cylindrical conduit provided to form a fuel passage to be supplied with fuel under pressurized high pressure from a high pressure pump, four injector sockets formed to contain therein a fuel injection valve and integrally fixed to the conduit and, and four cylindrical mounting bosses having mounting holes for attachment of the conduit to an engine head. In the fuel delivery pipe assembly, the fuel injector sockets are applied with a reaction force caused by fuel injected from the fuel injection valves into each cylinder of the engine. To retain the fuel injector socket in place against the reaction force, the mounting bosses are fixedly assembled with the conduit in a position adjacent the respective fuel injector sockets.
As the mounting boss is manufactured by cut-machining, the manufacturing cost of the delivery pipe assembly is increased due to increase of the material cost and machining cost of the mounting bosses. Because the fuel injector sockets and mounting bosses are separately assembled with the conduit, it is very difficult to enhance positioning precision of the component parts. This causes a problem in the assembly process of the component parts to the engine head.